harris



P. H. HARRIS ROTARY KILN March 10, 1964 2 Sheets-Sheet 1 Filed Nov. 22, 1960 \INVENTOR. PH/L /P H. HARP/S A T TOPNE VS P. H. HARRIS ROTARY KILN March 10, 1964 2 Sheets-Sheet 2 FIG- 4 Filed Nov. 22, 1960 INVENTOR. PH/L IP H. HARRIS A T TORNE VS United States Patent ()fiice 3,124,338 Patented Mar. 10, 1964 3,124,338 ROTARY KILN Philip H. Harris, Upland, Calif., assignor to American Cement Corporation, Los Angeles, Calif., a corporation of Delaware Filed Nov. 22, 1960, Ser. No. 71,099 4 Claims. (Cl. 26333) This invention provides an improvement in rotary kilns f the type used in heat treating pulverulent material such as lime and cement clinker.

For simplicity, the invention is described with specific reference to the manufacturer of Portland cement clinker, although it can be used in treating other materials.

In the manufacture of Portland cement clinker, finely divided calcareous and argillaceous materials are tumbled and fired to sintering temperature in a rotary kiln.

The conventional rotary kiln includes an elongated, hollow shell inclined slightly to the horizontal and mounted to be rotated slowly so that particulate matter slides around in it and moves slowly toward the lower end of the shell. Hot gas is passed through the interior of the shell to contact the particulate matter and raise it to the desired temperature. With such an arrangement there is low thermal efficiency because the hot gas contacts only a relatively small part of the raw materials, namely the exposed surface of the particulate matter, which is confined to a relative limited area in the lower portion of the kiln. Attempts have been made to improve thermal efficiency by the use of inwardly extending projections in the kiln to stir the particulate matter as the kiln rotates. Such attempts have met with difiiculty because of the relatively high gas velocities through the kiln and the fineness of the particulate matter. The stirring elements of the prior art tend to lift and drop the particulate matter into the gas stream, hereby aggravating the problem of dust collection. US. Patent 1,544,504 discloses an attempt to solve this problem by the use of inwardly extending projections which comb the particulate matter Without lifting it, but the patented system does not provide the thermal efiiciency desired.

This invention provides an improved rotary kiln in which the thermal efficiency is improved over that of the prior art, and which does not increase the problem of dust collection.

Briefly, the rotary kiln of this invention includes an elongated hollow shell which is mounted to rotate about its longitudinal axis. A plurality of plowing elements are mounted on the interior of the shell. Each plowing element has a cutting edge extending in the direction of rotation of the shell, and also has at least one turning surface adjacent the cutting edge. The turning surface is transverse to the direction of rotation of the shell in that the turning surface diverges from a transverse plane passing through the leading edge. Each point on the side of the turning surface diverging from the end of the leading edge adjacent the interior of the shell is located substantially closer to the transverse plane than a corresponding opposite point on the side of the turning surface diverging from the innermost projection of the leading edge. As the shell is rotated, particulate matter is plowed from adjacent the inner surface of the shell and rolled over on particulate matter which was perviously spaced from the inner surface of the shell.

Thus, as the kiln rotates the plowing elements move through the particulate matter and cause it to be turned over in place to expose fresh matter to the hot gas passing through the kiln. The turning of the particulate matter is confined to the immediate locality of each plowing element, and each plowing element is self-clearing so it does not carry any material above the central ilXiS of the kiln, thereby avoiding any increase in dust oss.

In the preferred form of the invention, each plowing element has a pair of opposed turning surfaces which are curved in the shape of the moldboard of a conventional plow to improve the turning and dumping efficiency of the element.

Preferably, each plowing element is removably attached to the shell so the elements can be replaced in case of damage or wear.

These and other aspects of the invention will be more fully understood from the following detailed description taken in conjunction with the accompanying drawings in which:

FIG. 1 is a fragmentary perspective view of the presently preferred embodiment of the invention;

FIG. 2 is a fragmentary side elevation of one of the plowing elements shown in FIG. 1;

FIG. 3 is a plan view of a plowing element taken on line 33 of FIG. 2;

FIG. 4 is a front elevation taken on line 44 of FIG. 3;

FIG. 5 is a side elevation of an alternate plowing element;

FIG. 6 is a plan view taken on line 66 of FIG. 5;

FIG. 7 is a sectional view taken on line 7-7 of FIG. 6; and

FIG. 8 is a forward elevation taken on line 88 of FIG. 6.

Referring to FIG. 1, a rotary kiln it) includes an elongated cylindrical and hollow shell 12 mounted on rollers 14 for rotation about its longitudinal axis, which is inclined slightly to the horizontal. The rollers 14 are driven by a conventional motor 15.

The interior of the shell is lined with conventional refractory material 16, such as fire brick. A plurality of inwardly extending plowing elements 18 are mounted on the interior of the shell and throughout its length.

As shown best in FIGS. 2 through 4, each plowing element 18 includes a V-shaped plow 25) which thas a narrow forward edge 22 pointed in the direction of rotation of the rotary kiln. As shown best in FIG. 2, the leading edge 22 extends upwardly and in the direction of kiln rotation so that the plow resembles the bow of a ship.

The V-shaped plow is welded to a plow plate 24, which is curved slightly to match the curvature of the inner surface of the refractory lining and the inner surface of a chair 26 to which the plow plate 24 is secured by nuts 28 and bolts 3d that extend through the shell and also hold the chair in place against the shell. As can be seen best in FIG. 3, the opposite sides 32 of the plow are inclined sli htly to the direction of the kiln rotation, and also extend inwardly and forwardly so that as the plow moves through particulate material in the kiln, the matter is piled up and turned over by each of the inclined turning surfaces 32 of the plow. Outer edge 33A of each side 32 is adjacent the interior of the shell; inner edge 33B of each side 32 is spaced inwardly from the interior of the shell. As particularly shown in FIG. 3, with respect to a transverse plane passing through leading edge 22, each point on outer edge 33A is located substantially closer to the transverse plane than a corresponding opposite point on inner edge 33B of the turning surface.

The inner ends of the bolts and the nuts on them are protected from damage by inwardly extending annular shrouds 34 mounted on the inner surface of the plow plate 24.

As can be seen in FIG. 2, the refractory brick includes a separate recessed space 36 to receive each chair which supports a plowing element. Each chair includes a triangular plate 37 (see FIG. 2) which is curved to match the curvature of the fire brick and be flush with it. Three outwardly extending webs 38 are formed integrally with the outer surface of the chair plate 37. Each web begins at a respective column 39 at each apex of the triangular plate, and merges with the other webs at the center of the plate. The outer edges 45 of the webs terminate short of the inner surface of the shell so that each chair is in contact with the shell at only the relatively small area of the outer ends of the columns to ridilllce heat transfer between the plow element and the s e The plowing elements can be of any suitable refractory material, such as stainless steel. Preferably, the chair is made of cast iron (0.664195% chrome; 1% Ni added).

In the operation of the apparatus shown in FIGS. 1 through 4, the kiln is heated before the material is introduced, so that by the time it reaches the plows, the inclined surfaces 32 are heated to aid in transferring heat to the material. As the plows move through the particulate matter, which is confined to the lowermost portion of the kiln, the hot turning surfaces 32 push through the material and tend to scoop it up and cause it to be turned over on itself so that the portion of material adjacent the refractory lining is lifted and turned over on top of material which previously had been spaced from the lining. In this way, the cooler material on the bottom is continuously rolled up to the top where it is exposed directly to the hot gas stream. Moreover, the heating of the material is enhanced by the contact with the hot turning surfaces, which are reheated as they travel through the upper portion of the kiln transverse to the direction of gas flow.

The plowing elements of this invention do not aggravate the dust problem because the particulate material is turned over substantially in place and without pushing it from one region to another because the inclined turning surfaces of the plowing elements dump the material after about one quarter of a revolution through it.

In the embodiment shown in FIGS. through 8, a plowing element 41 includes a rectangular base 42 shaped to fit in a recess (not shown) in the fire brick lining of a kiln. The outer surface 44 of the base is curved slightly to match the curvature of the interior surface of the kiln shell. A V-shaped plow 46 is mounted on the inner portion of the base, and includes a relatively narrow leading edge 48 which points in the direction of rotation of the kiln. The plow also includes a triangularly shaped downwardly and forwardly inclined top surface 50 that terminates with one apex of the triangle over the leading edge 48. The opposite sides 52 of the plow are of a concave shape similar to the moldboard of a conventional plow so that the sides 52 scoop and turn material as they move through it.

The plowing element shown in FIGS. 5 through 8 is adapted to be releasably secured in the kiln by bolts and nuts (not shown) extending through holes 54 in the base 42.

I claim:

1. A rotary kiln for treating particulate matter comprising:

(a) an elongated hollow shell,

(11) means for rotating the shell about its longitudinal axis, and

(c) a plurality of plowing elements mounted on the interior of the shell and having:

(1) a leading edge oriented in the direction of rotation of the shell and projecting inwardly from the interior of the shell, and

(2) two turning surfaces having an outer edge adjacent the interior of the shell and an inner edge spaced inwardly from the interior of the shell, each diverging from a transverse plane passing through the leading edge,

(3) each point on the outer edge of the turning surface being located substantially closer to the transverse plane than a corresponding opposite point on the inner edge of the turning surface,

(4) the plowing elements acting upon rotation of the shell to plow particulate matter from adjacent the interior surface of the shell and to roll it over on particulate matter spaced from the interior surface of the shell.

2. A rotary kiln for treating particulate matter comprising:

(a) an elongated hollow shell, (b) means for rotating the shell about its longitudinal axis, and (c) a plurality of plowing elements mounted on the interior of the shell and having:

(1) a leading edge oriented in the direction of rotation of the shell and projecting inwardly from the interior of the shell, and

(2) a pair of turning surfaces each adjacent the leading edge and having an outer edge adjacent the interior of the shell and an inner edge spaced inwardly from the interior of the shell, each diverging on opposite sides thereof from a transverse plane passing through the leading edge,

(3) each point on the outer edge of each turning surface being located substantially closer to the transverse plane than a corresponding opposite point on the inner edge of each turning surface,

(4) the area intermediate said edges of each turning surface having a concavity in the direction away from the transverse plane,

(5) the plowing elements acting upon rotation of the shell to plow particulate matter from adjacent the interior surface of the shell and to roll it over on particulate matter spaced from the interior surface of the shell.

3. A rotary kiln for treating particulate matter comprising:

(a) an elongated hollow shell,

(b) means for rotating the shell about its longitudinal axis,

(c) a plurality of plowing elements disposed on the interior of the shell, and

(d) releasable means securing the plowing elements to the shell, each plowing element having:

(1) a leading edge oriented in the direction of rotation of the shell and projecting inwardly from the interior of the shell,

(2) a pair of turning surfaces each adjacent the leading edge and having an outer edge adjacent the interior of the shell and an inner edge spaced inwardly from the interior of the shell, each diverging on opposite sides thereof from a transverse plane passing through the leading edge,

(3) each point on the outer edge of each turning surface being disposed substantially closer to the transverse plane than a corresponding opposite point on the inner edge of each turning surface,

(4) the plowing elements acting upon rotation of the shell to plow particulate matter from adjacent the interior surface of the shell and to roll it over on particulate matter spaced from the interior surface of the shell.

4. A rotary kiln for treating particular matter comprising:

(a) an elongated hollow shell,

(b) means for rotating the shell about its longitudinal axis,

(c) a refractory lining mounted on the interior of the shell to define a plurality of recesses,

(d) a mounting chair secured within each recess,

(e) a plowing element associated with each mounting chair, and

(f) means releasably securing each plowing element to its respectively associated mounting chair and securing each mounting chair to the shell, each plowing element having:

(1) a leading edge oriented in the direction of rotation of the shell and projecting inwardly from the interior of the shell,

(2) a pair of turning surfaces each adjacent the leading edge and having an outer edge adjacent the interior of the shell and an inner edge spaced inwardly from the interior of the shell, each diverging on opposite sides thereof from a transverse plane passing through the leading edge,

(3) each point on the outer edge of the turning surface being disposed substantially closer to the transverse plane than a corresponding opposite point on the inner edge of each turning surface,

(4) the area intermediate said edges of each turn- References Cited in the file of this patent UNITED STATES PATENTS 1,544,504 Tomlinson June 30, 1925 2,088,099 Venable July 27, 1937 FOREIGN PATENTS 904,512 Germany Feb. 18,, 1954 OTHER REFERENCES German Printed Application, 1,060,775, July 2, 1959,

of Horstkotter et a1. 

1. A ROTARY KILN FOR TREATING PARTICULATE MATTER COMPRISING: (A) AN ELONGATED HOLLOW SHELL, (B) MEANS FOR ROTATING THE SHELL ABOUT ITS LONGITUDINAL AXIS, AND (C) A PLURALITY OF PLOWING ELEMENTS MOUNTED ON THE INTERIOR OF THE SHELL AND HAVING: (1) A LEADING EDGE ORIENTED IN THE DIRECTION OF ROTATION OF THE SHELL AND PROJECTING INWARDLY FROM THE INTERIOR OF THE SHELL, AND (2) TWO TURNING SURFACES HAVING AN OUTER EDGE ADJACENT THE INTERIOR OF THE SHELL AND AN INNER EDGE SPACED INWARDLY FROM THE INTERIOR OF THE SHELL, EACH DIVERGING FROM A TRANSVERSE PLANE PASSING THROUGH THE LEADING EDGE, (3) EACH POINT ON THE OUTER EDGE OF THE TURNING SURFACE BEING LOCATED SUBSTANTIALLY CLOSER TO THE TRANSVERSE PLANE THAN A CORRESPONDING OPPOSITE POINT ON THE INNER EDGE OF THE TURNING SURFACE, (4) THE PLOWING ELEMENTS ACTING UPON ROTATION OF THE SHELL TO PLOW PARTICULATE MATTER FROM ADJACENT THE INTERIOR SURFACE OF THE SHELL AND TO ROLL IT OVER ON PARTICULATE MATTER SPACED FROM THE INTERIOR SURFACE OF THE SHELL. 